LAUSR

The profound impact of solar irradiance variations on the decadal variability of Earth’s climate has been investigated by previous studies. However, it remains a challenge to quantify the energetic particle precipitation (EPP) influence on the surface climate, which is an emerging research topic. The solar wind is a source of magnetospheric EPP, and the total energy input from the solar wind into Earth’s magnetosphere ( E in ) shows remarkable interdecadal and interannual variability. Based on the new E in index, this study reveals a significant interannual relationship between the annual mean E in and Eurasian cold extremes in the subsequent winter. Less frequent cold events are observed over Eurasia (primarily north of 50°N) following the higher-than-normal E in activity in the previous year, accompanied by more frequent cold events over northern Africa, and vice versa. This response pattern shows great resemblance to the first empirical orthogonal function of the variability of cold extremes over Eurasia, with a spatial correlation coefficient of 0.79. The pronounced intensification of the positive North Atlantic Oscillation events and poleward shift of the North Atlantic storm track associated with the anomalously higher E in favor the anomalous extreme atmospheric circulation events, and thus less frequent extreme cold temperatures over northern Eurasia on the interannual time scale. It is further hypothesized that the wave-mean flow interaction in the stratosphere and troposphere is favorable for the connection of E in signals to tropospheric circulation and climate in the following winter. 太阳活动是地球气候系统的基本能量源, 大量研究证实了太阳辐射强迫在年代际尺度上对气候的影响. 太阳变率主要影响气候的部分包括太阳光谱辐照度和高能粒子沉降(Energetic Particle Precipitation, 简称EPP). EPP的微粒主要来自太阳、大气磁层和外太空, 包括质子和电子等. EPP的不同成分对地表气候的影响是一个新兴的研究课题, 而主要的一个挑战是量化EPP对气候的影响. 来自太阳日冕洞的太阳风高速流是一种高能粒子, 以电子为主. 太阳风不能直接传到地表, 而是进入大气磁层, 并和磁层相互作用导致微粒的加速沉降. 但进入大气磁层的太阳风能量通量( E in )一直难以估算, 因此关于 E in 的气候效应的研究并不广泛. 直至近年来有利用三维磁流体动力模拟、行星际磁场和太阳风的条件推导出的能量耦合函数 E in . E in 不仅有年代际变率, 也具有年际变率. 基于此 E in 指数, 本文发现, 在年际尺度上, 年平均的 E in 与下一年冬季欧亚大陆的极端冷事件有显著的关联. 这也与以往主要关注太阳活动在年代际尺度上的气候效应的研究不同. 当进入大气磁层的太阳风能量通量偏高时, 下一年冬季欧亚大陆50°N以北的极端低温频次偏少, 对应的空间场类似欧亚大陆极端低温频次经验正交函数展开的主模态. 北大西洋涛动正位相和风暴轴的北移, 通过影响极端环流事件的发生频次, 有利于欧亚极端低温事件偏少. 对流层和平流层的波流相互作用则有利于 E in 的异常信号向对流层的传播.